1. Quiz Time #1
What is the formula for finding the area of a circle?

2. Лr squared

3. #2
What is the formula for finding the circumference of a circle?

4. Лd Or
2Лr

5. #3
Find the area.
7 cm

6. cm squared

7. #4
Find the area.
9 cm

8. cm squared

9. #5
What is the area?
8 cm
9 cm

10. 36 cm squared

11. #6
What is the area of a triangle with a base of 8 cm and a height of 2.61 cm?

12. 10.44 cm squared

13. #7
What is the area of the rectangle, if the area a triangle inside is 12 cm?

14. 24 cm squared

15. #8
The area of a triangle is 14 cm and the base is 7 cm. What is the height?

16. 49 cm squared

17. #9
What is the area of a circle with a radius of 3 cm?

18. 28.26 cm squared

19. What is the area of a parallelogram that has a base of 17 ft and a height of 36 ft?

20. 612 ft squared

21. Interpreting them and drawing them
Circle Graphs
Interpreting them and drawing them

22. A circle graph shows data as parts of one whole.
Each sector of a circle graph represents a percent of the whole cirle.
The whole circle represents 100%.

23. Parts of a Circle Graph All circle graphs have a TITLE.
Each sector is labelled with a category and a percent.
A circle graph compares the number in each category to the total number.
Sometimes there is a legend that shows what category each sector represents.

24. Sample Circle Graph

25. Circle Graph with Legend

26. Definitions
A percent circle is a circle broken into 100 equal parts. Each part represents one percent.
The sum of all the angles in a circle is 360 degrees. These are called central angles.
A central angle may also be called a sector angle.

27. Sometimes you are asked to find the angles of a category within a circle graph.
This is how you do it.

28. Problem
Students in grade 7 were asked how they got to school each day. 9 rode their bikes, 11 walked, 17 rode the bus, and 13 were driven by car.
First, write each number as a fraction out of 50. (Because there are 50 students)

29. The circle graph will then represent all the types of transport.
To put fractions into the percent circle, convert all fractions to a percent. The sum should be 100%.
You can now graph the results in a percent circle.

30. To find the angles of each category, convert the percent to a decimal.
18% = .18
Multiply the decimal by 360 degrees.
Round to the nearest whole number.
.18 x 360 = 64.8 = 65 degrees.

31. Once you have determined the angles for each category, the sum of all the angles should be 360 degrees.
To draw the circle, use a compass.
Use a protractor to construct each central angle.

32. Start with the smallest angle.
Draw a radius and measure the distance of the angle.
Start the next angle where the other one finished.
Label each sector with a name and percent.
Write a title for the graph.